Well had a few shots with it and grouping is terrible first group was 10 shots and they spread over about 2 1/2 inch chrono said 16fps difference highest out the 10 shots was 564 FPS lowest was 548 put another 50 shots through and did another 10 shots group was about 2 inch and chrono says 13 FPS difference high being 570 FPS low being 557
Currently have it stripped for investigation